At the present time, the boring of a workpiece on two different centers is accomplished by use of two different cutting tools on a rotating tool head. The tool head bores and faces on one centerline, and then retracts and bores and faces again on a second centerline. Alternatively, separate tools on separate tool heads may be employed. The tool setup must be made with great precision and frequent tool adjustment is required due to uneven tool wear. There is a special problem in situations where the cutting action of the tools overlap, because it is difficult to adjust the tools and to adjust for wear in order to eliminate formation of a step in the blended face.
In accordance with the present invention, the workpiece rotates. A single tool fixed on a set of contouring compound slides found on any conventional lathe can do all of the multiple boring and facing and even turning on both part centerlines in one chucking. All part features are adjusted and controlled by programing of the lathe slides. Only one tool adjustment for wear is required, reducing setup time and insuring the removal of metal with great precision.
In accordance with the present invention, a work holder is mounted on a spindle shaft adjacent to a cutting tool in different positions spaced laterally relative to the spindle shaft axis. The cutting tool may bore and face the workpiece when the work holder is mounted on the spindle shaft in one position, and then in a second metal cutting operation the tool may bore and face the workpiece while the work holder is in a different position on the spindle shaft.
More specifically, the means for mounting the work holder on the spindle shaft comprises an eccentric socket in the end of the spindle shaft and an eccentric post on the work holder rotatably received in the socket. The workpiece may be shifted to different positions for cutting by merely rotating the work holder about the eccentric axis of the socket.
These and other objects of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying drawings.